Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – For extrusion or injection type shaping means
Reexamination Certificate
2002-06-19
2004-11-09
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
For extrusion or injection type shaping means
C425S19200R, C425S326100, C425S388000
Reexamination Certificate
active
06814559
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a shaping apparatus for an extrusion system.
2. The Prior Art
A shaping device for an extrusion system is known from patent specification U.S. Pat. No. 4,181,487 A, which comprises at least one calibration apparatus with several plate-type sizing units arranged one after the other in the direction of extrusion. The individual sizing units arranged one after the other having a sizing orifice with several sizing surfaces to which the article being drawn through conforms in an engaging arrangement. These individual sizing units have end faces running in a direction more or less vertically and perpendicular to the sizing surfaces and channels are provided, recessed back from the sizing surfaces, in at least one of the end faces, which extend via a distribution channel to an accumulator channel. When the sizing units are placed side by side, these channels form a plurality of cavities, by means of which a pressure differential can be generated at various points of the article as it is fed through. These individual sizing units are made up of a plurality of hollow jacket-type components, through which a cooling medium flows so that the heat absorbed by the sizing units from the article is fed from the sizing units via the region of their outer side faces. The disadvantage of this design of sizing units is that it is not always possible for the article to be satisfactorily calibrated in every type of application.
Other shaping devices for extrusion systems are known from patent specifications DE 199 17 837 A1 and DE 297 16 343 U1 filed by the same applicant, and consist of at least one calibration device comprising in particular a plurality of calibration dies disposed one after the other in the direction of extrusion, this calibration device and/or the calibration dies being provided with cooling ducts through which a coolant is circulated. The calibration device also has shaping surfaces to which an article conforms as it is fed through, a sealing device being provided at least between the extrusion tool of the shaping apparatus, such as a nozzle for example, and the first calibration die immediately following it in the extrusion direction, to form a cavity which seals off the outer surface of the article from the ambient pressure as it is fed through. However, this sealing arrangement for forming an additional cavity may also be arranged between the first calibration die and at least one other calibration die. These calibration dies are designed in a block construction and it is not always possible for the article to be satisfactorily calibrated in every type of application using this design.
Shaping apparatus is also known in which the plastic lengths of sections, in particular hollow sections or tubes, are calibrated to the desired external and internal dimensions as they leave an extrusion nozzle and are frozen to the desired external dimensions or cooled to the requisite temperature to produce the desired rigidity. Shaping systems of this type are described in the book, “Extrusionswerkzeuge für Kunststoffe und Kautschuk” by Walter Michaeli, published in 1991 by Carl Hanser Verlag, Munich/Vienna, 2nd completely revised and extended version, in particular pages 321 to 329. Page 323 provides an illustration of an external vacuum calibration system, whereby the extruded material leaving the extrusion die in the form of a hollow section is fed into a calibration die at a distance from the point at which it leaves the nozzle lip of the extrusion apparatus, through which extruded material is fed so that the region of its peripheral external surface conforms to the shaping surfaces of the calibration die. The surface of the extruded material is able to engage on the individual shaping surfaces of the calibration die without any clearance due to air inlets, in particular slots, in the shaping surfaces, which communicate via supply lines with a vacuum source. In order to cool the extruded material, the calibration dies are provided with one or more peripheral passages for a cooling medium and the vacuum can be increased in the individual air inlets or slits the farther away they are in distance from the nozzle lip of the extrusion apparatus. The temperature of the cooling medium is very low compared with the mass temperature of the extruded section and is approximately 20° C. In so-called dry calibrators of this type, it is common practice to provide one or more cooling baths, in which the sufficiently rigid sections are cooled to ambient temperature, partly by applying a vacuum and wetting using spray nozzles or by passing them through water baths. With calibration apparatus of this type, it is not possible to obtain a sufficiently high surface quality on the finished extruded material in many cases once the shaping device has been in service for any length of time.
SUMMARY OF THE INVENTION
The underlying objective of the present invention is to propose a shaping apparatus, in particular a calibration system, by means of which the article being fed through is uniformly and rapidly cooled by virtually the entire circumference of the calibration orifice.
This objective is achieved by the invention with a shaping apparatus for an extrusion system with at least one calibration device comprising means for dispersing heat and at least one calibration die with several calibration units disposed one after another in an extrusion direction. Each calibration unit has at least one calibration orifice with several shaping surfaces which come into contact with an article fed therethrough, end faces spaced apart from each other in the extrusion direction, and side faces extending between the end faces, a first end face being directed towards an inlet region and a second end face being directed towards an outlet region of the article fed through the calibration orifice. At least one cavity is formed between two immediately adjacent calibration units, the cavity extending from a respective one of the shaping surfaces to, and opening into, a passage. The calibration orifice is provided with at least one continuous circulation passage around a predominant part of, and immediately adjacent to, the circumference thereof, the circulation passage having a separate inlet and outline line, extending across a predominant distance of a thickness between the two end faces of the calibration unit and being closed in the region of the end faces, the circulation passage is provided with at least one transverse passage along the circumferential extension thereof extending across a predominant distance of the thickness between the end two faces, the transverse passage being closed at the region of the two end faces and having a flow connection to the circulation passage via at least one connecting passage, and a baffle system projects from the connecting passage in a direction opposite the calibration orifice, at least in certain regions, into the flow cross-section of the circulation passage.
The surprising advantage of this solution resides in the fact that every calibrating unit or units is provided with a separate circulation passage in the region of the calibration orifice, which runs inside the calibration unit without any connection to a delimiting external face thereof other than the inlet and outlet lines. Consequently, virtually the entire circumference of the calibration orifice can be cooled by the coolant fed through the circulation passage. It can be arranged immediately along and adjacent to the shaping surfaces, and the cavities provided between the end faces of immediately adjacent calibrating units can be designed so as to run around almost all or all of the circumference of the calibration orifice. Furthermore, heat is fed away from virtually the entire thickness of the calibration unit in the region of the shaping surfaces because the circulation passage can be disposed right in the region of the two end faces spaced at a distance apart from one another. Also, in areas of the profiled section which are difficult to coo
Collard & Roe P.C.
Greiner Extrusionstechnik GmbH
Heitbrink Tim
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